Surprisingly (I just benchmarked it myself), the times are near the same.

Here's my benchmark (in case I made a mistake):

  import time

  def combine(upper,lower): return (2**32)*upper + lower
  def combine2(upper,lower): return (upper << 32) | lower

  def test_combine():
  	start = time.clock()
	for i in range(10000000):
		combine(i,i)
	end = time.clock()
	output = 'The time taken for combine() is ' + str(end - start)
	print output

  def test_combine2():
	start = time.clock()
	for i in range(10000000):
		combine2(i,i)
	end = time.clock()
	output = 'The time taken for combine() is ' + str(end - start)
	print output

Also see http://wiki.python.org/moin/PythonSpeed/PerformanceTips#Pyth...

That's surprising; it's more than twice as slow in Ruby (yeah, yeah). It's also (for obvious reasons) orders of magnitude faster in C --- if you were crazy enough to actually write code that way.

I don't know much about Python so forgive me if this is stupid - but could 2^32 have been optimized as a constant, so that the result is just a multiplication and an addition?

Okay okay ... I should have written:

import math; math.pow(2,32)

I tried to use the double star operator, but that is markup for italics in this software, so it was edited out.